This invention relates to a thermoplastic copolyamide useful as a molding compound, more particularly it is a transparent, ethanol resistant, hot water resistant, thermoplastically formable copolymer of predominantly epsilon-caprolactam with small portions of a cyclic and/or aromatic amide as copolyamide.
In the following discussion of the compounds used to create the copolymers of this invention, all the patents listed below are hereby incorporated by reference, in toto.
The preferred diamine to be combined with a diacid, to form the aromatic and/or cyclic copolyamide, bis(4-aminocyclohexyl)methane, also known as PACM, is disclosed in U.S. Pat. No. 2,512,606 (column 4). The lower alkyl substituted PACM is disclosed in U.S. Pat. No. 2,516,585 (column 3). Also preferred are the diamines 1,3 or 1,4-cyclohexane bis(methylamine), known as BAMCH, disclosed in U.S. Pat. No. 3,012,994 (column 9 and in Example 10). The compounds 1,3 or 1,4-cyclohexane bis(ethylamine) or (propylamine) could be prepared by the same method. The compounds meta and para-xylene diamine, (MXDA or PXDA) are disclosed in U.S. Pat. No. 2,985,628. The diamine 1,4-diaminocyclohexane is disclosed in U.S. Pat. No. 3,794,625 (column 2). The BAMCH analog 2,2-bis(amino cyclohexyl)propane and 2,2-bis(amino lower alkyl cyclohexyl)propane are disclosed in U.S. Pat. No. 3,840,501. The para,para'-methylene dianiline is disclosed in U.S. Pat. No. 4,065,441. The compounds meta and paraphenylenediamine also known as PDA are disclosed in U.S. Pat. No. 3,554,966. U.S. Pat. No. 3,794,625 also discloses 1,3 cyclohexane diamine while U.S. Pat. No. 4,207,411 discloses 1,4-cyclohexane diamine, terephthalic acid (TPA), and isophthalic acid (IPA). The compounds 2,5 and 2,6-bis(aminomethyl)bicyclo-[2,1]heptane, also known as norbornanes, are disclosed in U.S. Pat. No. 3,876,585. The compounds, 2,4 and 2,6 metatoluene diamine, are disclosed in U.S. Pat. No. 4,072,665. The dicarboxylic acid of 1,4-cyclohexane dicarboxylic acid is also disclosed in U.S. Pat. No. 2,985,628. A series of naphthalene dicarboxylic acids are disclosed in U.S. Pat. Nos. 3,992,360, 4,012,365, and 3,554,971. Toluene diisocyanate is disclosed in U.S. Pat. No. 4,087,481 and methylene diphenyldiisocyanate is disclosed in U.S. Pat. No. 4,072,665. Paraaminobenzoic acid or PABA is readily available as a commercial product used for instance in suntan lotion. PABA can be copolymerized by the method of U.S. Pat. No. 3,673,143.
Various PACM and BAMCH copolymers with diacids such as TPA and IPA and other amides further copolymerized with epsilon-caprolactam are known in the art. PABA or aromatic diamines and diacids may be reacted according to the catalytic method as in U.S. Pat. No. 3,408,334, hereby incorporated by reference. The listing in Table I of prior art patents attempts to capsulize the state-of-the-art for the preferred PACM and BAMCH copolymers. All the patents listed below in Table I are also hereby incorporated by reference, in toto.
TABLE 1 ______________________________________ Weight % Patent Number Copolymer Additive of Nylon 6 ______________________________________ U.S. 3 847 877 PACM-TPA 30-65 E. German 130 790 PACM-TPA 66-99 Japan 49-1008 PACM-TPA 80-97 Japan 54-123197 PACM-TPA or IPA 70-98 U.S. 2 985 626 BAMCH-TPA about 30-62 U.S. 4 071 506 BAMCH-TPA 5-60 U.S. 3 012 994 BAMCH-TPA or IPA None U.S. 3 942 360 BAMCH-TPA or IPA + less than Aliphatic 50 U.S. 3 597 400 PACM-TPA or IPA-HMDA* none Japan 054739 BAMCH + Adipic Acid & HMDA + TPA none ______________________________________ Properties Hot Water Alcohol Patent Number Clear Resistance Resistance ______________________________________ U.S. 3 847 877 Yes Yes Insoluble in methanol E. German 130 790 Yes -- -- Japan 49-1008 used in composite stretch fiber Japan Yes Does not Does not 54-123197 dissolve dissolve U.S. 2 985 626 Yes -- -- U.S. 4 071 506 Yes -- -- U.S. 3 012 994 -- -- -- U.S. 3 942 360 Yes -- -- U.S. 3 597 400 Yes No Tested in methanol Japan 054739 Yes -- -- ______________________________________ *Hexamethylenediamine
Applicants have discovered that for acceptable alcohol resistance, and for proper hot water resistance, combined with good transparency, there is a narrow and critical range of the weight percentage of epsilon-caprolactam, nylon 6, which can be present in the copolymer amide of this invention. See the figure showing the typical copolyamide of this invention, PACM-T in nylon 6 using PACM having a 20 percent trans, trans isomer content. Note that all the desired properties are only available in the copolyamide of this embodiment of this invention between 12.3 and 19.6 weight percent (4.5 to 7.5 mol %) of PACM-T and conversely between 80.4 and 87.7 weight percent of the nylon 6 copolyamide.